The no-monitor option for services

September 14, 2018

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If you use an external system to perform health checks on the services and do not want the NetScaler appliance to monitor the health of a service, you can set the no-monitor option for the service. If you do so, the appliance does not send probes to check the health of the service but shows the service as UP. Even if the service goes DOWN, the appliance continues to send traffic from the client to the service as specified by the load balancing method.

The monitor can be in the ENABLED or DISABLED state when you set the no-monitor option, and when you remove the no-monitor option, the earlier state of the monitor is resumed.

You can set the no-monitor option for a service when creating the service. You can also set the no-monitor option on an existing service.

The following are the consequences of setting the no-monitor option:

If a service for which you enabled the no-monitor option goes down, the appliance continues to show the service as UP and continues to forward traffic to the service. A persistent connection to the service can worsen the situation. In that case, or if many services shown as UP are actually DOWN, the system may fail. To avoid such a situation, when the external mechanism that monitors the services reports that a service that is DOWN, remove the service from the NetScaler configuration.

If you configure the no-monitor option on a service, you cannot configure load balancing in the Direct Server Return (DSR) mode. For an existing service, if you set the no-monitor option, you cannot configure the DSR mode for the service.

To set the no-monitor option for a new service by using the CLI

At the command prompt, type the following commands to create a service with the health monitor option, and verify the configuration:

To set the no-monitor option for an existing service by using the CLI

At the command prompt, type the following command to set the health monitor option:

set service <name> -healthMonitor (YES|NO)

Example:

By default, the state of a service and the state of the corresponding monitor are UP.
>show service LB-SVC1
LB-SVC1 (10.102.29.5:80) - HTTP
State: UP
1) Monitor Name: http-ecv
State: UP Weight: 1
Probes: 99992 Failed [Total: 0 Current: 0]
Last response: Success - Pattern found in response.
Response Time: 3.76 millisec
Done
When the no-monitor option is set on a service, the state of the monitor changes to UNKNOWN.
set service LB-SVC1 -healthMonitor NO
Done
show service LB-SVC1
LB-SVC1 (10.102.29.5:80) - HTTP
State: UP
Last state change was at Fri Dec 10 10:17:37 2010.
Time since last state change: 5 days, 18:55:48.710
Health monitoring: OFF
1) Monitor Name: http-ecv
State: UNKNOWN Weight: 1
Probes: 100028 Failed [Total: 0 Current: 0]
Last response: Probe skipped - Health monitoring is turned off.
Response Time: 0.0 millisec
Done
When the no-monitor option is removed, the earlier state of the monitor is resumed.
> set service LB-SVC1 -healthMonitor YES
Done
>show service LB-SVC1
LB-SVC1 (10.102.29.5:80) - HTTP
State: UP
Last state change was at Fri Dec 10 10:17:37 2010
Time since last state change: 5 days, 18:57:47.880
1) Monitor Name: http-ecv
State: UP Weight: 1
Probes: 100029 Failed [Total: 0 Current: 0]
Last response: Success - Pattern found in response.
Response Time: 5.690 millisec
Done

To set the no-monitor option for a service by using the GUI

Navigate to Traffic Management > Load Balancing > Services.

Open the service, and clear Health Monitoring.

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